There exists a need for water purification devices, for use by campers, travellers and the like on the one hand, and for use in certain emergencies, such as nuclear accidents, release of accidental or intended nature of poisonous substances and the like. Thus, there exists a need for the nearly absolute removal of noxious and nuclear contaminants, and also a need for the provision of potable water from contaminated water sources. One of the existing problems is the reliable indication whether the purification system is still fulfilling its task or not; such devices have a limited purification capacity, and the exhaustion of these must be indicated in a reliable manner. Many existing purification systems use ion exchange resins, in combination with active charcoal filters, mechanical filters, etc. It is conventional to incorporate means for changing the color of the resin when the capacity of the purifier to effect water purification becomes exhausted. Such color change of resins is disclosed amongst others in U.S. Pat. No. 2,935,194 and U.S. Pat. No. 980,335.
Water contamination is a serious problem, and this has been demonstrated on a large scale by the Tchernoville nuclear accident, by the accidental release of poisons into the Rhine, by the large scale contamination of rivers and lakes by nitrates and also by effluents of chemical industry, and also by pesticides, and the like.
Reliable and easily perceived indication of the exhaustion of the purification capacity of a purification device for the provision of potable water is of great importance. According to the invention such means are provided, based on the coloring of the water issuing from the device when this is not purified to the required degree of purity. This may be used with any water purification system and for water purity testing. Furthermore, it is of importance to provide water purification means which can be stored over prolonged periods of time and which can instantly be used when required. Such means, in the form of kits of two units, which have to be attached to each other, are provided according to this invention. Such purification devices are provided with color indicators of the type defined above.